JPS5842999B2 - color television equipment - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to color television systems, and particularly to color television systems that detect the presence or absence of a color signal on each line, such as a SECAM signal.

BACKGROUND OF THE INVENTION SECAM (Sequential Color Signal and Memory Television)
In the system, the subcarrier is alternately frequency modulated with a line period of 64 microseconds (1/15625H2) by weighted color signals, which are first and second color difference signals.

A utilization device such as a television device separates the luminance and subcarrier signals from this modulated signal, demodulates the subcarrier, and applies these demodulated signals to a matrix circuit.

For this purpose, since the subcarriers are switched alternately in the line period, in addition to the first chrominance signal of the current line, a second chrominance signal is required from a storage device that stores the subcarriers added in the previous line period. It is necessary to obtain it.

Since a color discrimination signal is inserted during each field blanking period, this color discrimination signal can be used to button and synchronize line rate switches on the utilization device.

Such a line rate switch applies the delayed and undelayed subcarrier signals to the appropriate demodulators to obtain the correct input signal to the matrix circuit (details can be found in the 1969 Irifue Book of Radio Technology). "Color Television" Volume 2rP by B. Nis Kant and G.B. Townsend, first edition published by
ALXSECAM and Other Systems," pages 179-220.

). The color subcarriers of the television systems described above can vary in amplitude over a wide range.

Therefore, on the receiving side, it is necessary to maintain the output of the discriminator within the limits of the device using a high gain □ vine.

These limits are the normal operating voltage applied to the input of the decoder and
It is defined as the ratio of the voltage corresponding to a specific percentage reduction in the amplitude of the demodulated signal.

This high gain limiter generates noise when no color signal is present at the input, making it very difficult to determine whether the device has a poor signal-to-noise ratio or no signal is being applied to the device. Met.

If an error occurs in determining whether no color signal is being applied to the device or whether the signal-to-noise ratio is poor, the device will not be able to accurately observe the television signal.

To overcome this drawback, the vertical line discrimination signal is SEC
Added to AM signal.

Proposals to change the composite SECAM signal format (elimination of these vertical line discrimination signals) again lead to the drawback of not being able to make accurate observations, and no effective solution yet exists.

Furthermore, as mentioned above, most SECAM decoders and encoders utilize a vertical line discrimination signal that is present during the vertical retrace interval, but such signals have now been removed from composite SECAM systems, so that the first and second Only the white reference signal inserted on the back porch is available to determine the line order for the color difference signals and to disable the color killer circuit.

However, when the white reference signal for color synchronization is used to detect the presence or absence of a color signal, a problem arises in that noise is generated in the portion (line) where the white reference signal is not inserted, as in the case of color signal detection.

Furthermore, since the insertion positions of the vertical line discrimination signal and the white reference signal are different, detection of the presence or absence of a color signal based on the white reference signal is different from the case where the vertical line discrimination signal is used.

Therefore, the synchronization circuit of the device used had to detect the presence or absence of a color signal using any of the methods described above, but since the composite SECAM signal does not always satisfy the required tolerance, these methods are not suitable. Conventional circuits using

Also, as is well known, NTSC, PAL, and SECAM.

There are many principles that can be applied to most, if not all, television systems in use today, such as ART, NIR, etc.

For example, in the SECAM system, the color signal subcarrier is 5.
It is suppressed for a period of 7±0.3 microseconds.

Such a period begins with the line suppression signal and ends with the onset of the synchronization signal (rSEC, published by Nord Graphics, Paris).
AM Color Television System)
.

If this suppression period is used to detect the presence or absence of a color signal, a complicated circuit is required to determine the timing, etc., which has the disadvantage that the device becomes expensive and complicated.

OBJECTS OF THE INVENTION Accordingly, one of the objects of the invention is to provide a color television device which overcomes the drawbacks of the prior art.Another object of the invention is to provide a color television device that can control the presence or absence of a color signal depending on the system standard of the television signal. An object of the present invention is to provide a flexible color television device that can be preprogrammed with information related to the present invention.

Still another object of the present invention is to provide a color television device that can detect the presence or absence of a color signal without being affected by noise.

SUMMARY OF THE INVENTION According to the color television device of the present invention, the presence or absence of a color signal that can be switched on each half line of one field of the television signal, depending on the television signal system standard (for example, SECAM). (hereinafter referred to as color information).

) is stored in the storage means in advance.

Further, the address signal generating means generates an address signal for the storage means by counting pulse signals having a repetition frequency twice that of the horizontal pulse of the television signal.

The contents of the storage means are read out using this address signal, and color information regarding the presence or absence of a color signal is obtained.

Also, when the vertical pulse of the television signal is generated, if the address signal is pressed in an odd field, the first initial value is set, and if the address signal is pressed in an even field, the second initial value is set, which differs in the least significant bit from the first initial value. , the color information from the storage means is accurate even if the television signal is offset by one-half line for each field due to interlaced scanning.

Furthermore, the storage means is 1 (instead of 2 fields worth of color information)
It is only necessary to store color information for one field.

Therefore, accurate color information regarding the presence or absence of a color signal can be obtained without being affected by noise.

If this color information is used, for example, in a color filter, images displayed on a color cathode ray tube will not be affected by noise, and television signals can be accurately measured.

Embodiments of the Invention Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a color television device according to the present invention.
FIG. 2 is a block diagram when applied to the M system.

A composite SECAM video signal (television signal) is applied to input terminal 10.

Such a video signal consists of a subcarrier signal that is alternately modulated every line period by a luminance signal and two color difference signals.

The input terminal 10 is connected to a video intensification and luminance signal delay stage 12, a bandpass filter and "Bell" stage 14, and a synchronization and timing stage 16 (synchronization means), and the composite video signal is processed as before. .

A bandpass filter and "bell" stage 14 removes the luminance signal from the composite video signal and separates the chrominance signal (hereinafter chrominance signal is a subcarrier signal modulated alternately by two color signals for a specified period of time). , the amplitude of the modulated subcarrier is restored by the opposite characteristic used to pre-emphasize the color subcarrier at the encoder.

The video enhancement and delay stage 12 processes the luminance signal component of the composite video signal to produce a monochromatic signal E delayed by the same amount of time it takes for the narrowband monochromatic signal to pass through each of the remaining stages (circuits) of the device. 'Y is generated as an output signal.

This monochromatic signal E'Y, which is used for both color and monochrome displays, is applied directly to a matrix 20 and a utilization device 18, such as a color cathode ray tube.

Synchronization and timing stage 16 processes the luminance signal component of the composite video signal to separate synchronization information from the luminance signal component.

Such information is, for example, horizontal blanking pulses, vertical blanking pulses, and horizontal (line) and vertical (field) synchronization pulses.

The chrominance signal with subcarriers restored to the correct amplitude by the bandpass filter and "bell" stage 14 is divided into a red signal minus the luminance signal (E'RE'y) and a blue signal minus the luminance signal (E'RE'y).
It consists of two sequential FM color difference signals corresponding to (E'B-E'y).

Such color difference signals are hereinafter referred to as D'R and D'B, shall be.

Note that when the subcarrier is modulated, a negative value of E'R-E'Y gives a positive frequency deviation, so a negative sign for D'R is required.

Furthermore, the button has a gamma correction signal at 75% of the highest value.
For a 00% pure color signal, based on the European Broadcasting Union (EBU), which recommends color-per-color signals, the coefficients 1 and 2 are ``1'' for D'□ and D'B.

As described above, signals D'□ and Df8 are transmitted sequentially.

That is, if the time between synchronizing pulses is defined as a line, the D'R line is followed by the D/8 line.

Signals D'R and D'B are then applied to synchronization and timing stage 1.
6 is added to a prelimiter stage 22 which is controlled by an inhibit signal derived from 6.

Signals D'□ and D'B are thus limited within amplitudes determined by subsequent stages to prevent or minimize, for example, crosstalk or other degrading characteristics well known to those skilled in the art.

The limiter 22 is inhibited from operating during horizontal synchronization of the composite video signal, for example, to prevent spurious noise from passing through the device.

The device further transmits a color difference signal, namely D'□ or D/8.
The color difference signal transmitted in the previous line is outputted by a storage stage 24 which continuously stores one of the color difference signals transmitted in the previous line.

Therefore, a delay line can be used in the storage stage 24.

The sequential switch 26 receives the signal from the storage stage 24 and the signal D transmitted directly via a line 28 bypassing the storage stage 24.
Since 'R and D'B are added, it is possible to sequentially press the inputs of switch 26 to obtain both signals D'R and D'B at the same time.

The delay time of storage stage 24 is equal to one scan line period or 64 microseconds.

Sequential switch 26 may be an electronic or logic switch, and the signals D' and D'B from sequential switch 26 are sent to demodulation circuits 30, 32 comprising limiter, discriminator and de-emphasis circuitry.

Basically, it does not matter whether the signal is added after a delay or directly, the sequential switch 26 ensures that the signal D'R is always added to the D'R demodulation circuit 30 and the signal D'B is demodulated to D'B. Add to circuit 32.

In conventional systems, switch 26 controls switch control stage 34 in response to line frequency pulses or field pulses.
(line frequency pulses and field pulses are obtained from the synchronization and timing stage 16).

). For details, see the above-mentioned document ``Color Television''.
Please refer to

Signals D'R and D'B from sequential switch 26 are width limited and demodulated by a conventional gate and discriminator, but the discriminator's bandwidth is wider than, for example, an NTSC demodulator.

The demodulated signals D'□ and D'B are then de-emphasized with the inverse characteristics used in the encoder, and their gains are adjusted in relation to the E'Y signal already mentioned.

As is well known, demodulation circuits 30 and 32 may include a discriminator that generates a signal that tracks the input FM signal using a voltage controlled oscillator using a phase-locked loop.

The phase comparator of the phase-locked loop is the loop's error detector and produces an output voltage proportional to the sine of the phase difference of the voltage controlled oscillator and the input FM signal.

The output of the demodulation circuit is then passed through a conventional "color killer" stage 36.
is added to matrix 20 via.

Therefore, the output of the demodulation circuit is combined with the signal E'Y, and in addition to the color difference signals (E'RE'Y) and (E'B - E'y), the third color difference signal (E'o E'y) is also generated. Occur.

These three color difference signals are transmitted to the utilization device 18 along with the signal E'Y.
added to.

Therefore, if the utilization device 18 is a color picture tube, the signal E/
The beam current generated by Y is proportional to the color signals corresponding to red, green and blue, resulting in a color image.

The above-mentioned system is based on the well-known SEC described in the above-mentioned literature.
The AM decoder is US Pat. No. 3,863 by Nelson et al.
It can also be done as detailed in No. 264 (corresponding to Japanese Unexamined Patent Publication No. 50-19327).

However, the invention is also applicable to SECAM systems or other television signal system standards.

The present invention adds to the prior art in a variety of new and effective ways.

Referring further to FIG. 1, around the synchronization and timing stage 16 there is a
A device according to the invention is arranged which is preprogrammed for each line and generates color information regarding the presence or absence of a color signal.

This device makes an instantaneous determination whether each half line of the composite signal has a color signal.

The device of the invention comprises a synchronization and timing stage 1 which is a synchronization means.
6 includes a counter stage 38 which is an address signal generating means responsive to the output provided from 6.

The output from the synchronization means is preferably at line frequency (15,6
25Hz) and a pulse train (hereinafter referred to as H) that occurs at 31
This is a vertical pulse train (hereinafter referred to as ■) that occurs every 2.5 lines, ie, every 20 milliseconds.

These H and ■ pulses, SECAM sequential signals, etc.
The field blanking period of the SECAM signal is shown in FIG.

As can be seen from this figure, the duration of the vertical pulse begins at a predetermined portion of the sawtooth vertical sync pulse (the sawtooth signal obtained by feeding the sync signal to the integrator circuit) during the field blanking period, which is Fields 2 and 4 start from half the line, and fields 2 and 4 start from the beginning of the line.

Since the generation of the H and ■ signals is well known, a detailed explanation will be omitted.

Counter stage 3B is an N-bit counter consisting of a plurality of 4-bit binary counters and is connected to address bus 40 (N
- an address signal (data word) for a FROM (programmable read-only memory) 44 which is a storage means for M) bits, and an address signal (data word) for an M-bit multiplexer 46 on an address bus 48;
(M and N are regular, and N is more accurate than M).

FROM 44 responds to the (NM) bit address signal.

The FROM 44 may store color information regarding the presence or absence of color signals according to the television signal system standard.
This FROM 44 acts as firmware.

This firmware is programmable and gives flexibility to the system.

The data (color information) stored in FROM 44 is then read out onto data bus 42.

Multiplexer stage 46 sequentially selects each of the parallel bits of data from FROM 44 in response to the lower M bits of the address signal from counter stage 38 provided via multiplexer address bus 48.

The output of multiplexer stage 46 is then applied to synchronization and timing stage 16 (the purpose of which will be described below) and via a color enable control stage 86, described below.
A "color killer" stage 36 is also added to allow matrix 20 to mix the color signals only during lines that have color signals.

Therefore, color information indicating whether each half line has a color signal is programmed into the FROM 44 in accordance with the television signal system standard.

Thus, a color television device according to the invention is obtained which outputs preprogrammed color information between each half line determined according to the system standard of the television signal.

In the present invention, the presence or absence of a color signal for each line is programmed in advance.

By the way, for interlaced scanning, it is also important to detect the presence or absence of a color signal in the half line at the beginning and end of each field.

If the half-in at the beginning and end of each field is not important, the PROM 44 only needs to store one field's worth of color information, reducing storage capacity and the number of address bits. If the first and last half lines of each field are important for scanning, PR
The OM 44 must store color information for two fields, which increases the storage capacity and the number of address bits.

However, according to the present invention, color information for one field is stored in PROM.
44, it is possible to reliably obtain color information that can be pressed on a half line at the beginning and end of each field in consideration of interlaced scanning.

Therefore, the capacity of the storage means and the number of bits of the address signal can be reduced, and the structure can be made compact, simple, and inexpensive.

The present invention having such effects will be explained in more detail with reference to FIG.

In FIG. 3, a counter 38, which is an address signal generating means,
The storage means PROM 44 and multiplexer 46 are shown in detail.

Three 4-bit binary counters 38A, 38B, 38C, preferably commercially available 748163 type integrated circuits (ICs), are connected to the synchronization means 1 via an input terminal 50 and a NOR gate 52.
It is simultaneously clocked (via the clock terminal (CK)) by the H pulse applied from 6 to 6.

The NOR gate 52 corrects the polarity of the clock signal and also locks the counter with a pulse train of 31250 Hz, which is twice the frequency of the H pulse.

Such a 31250 Hz pulse train is obtained by triggering the multivibrator 51, which is a pulse generating means, with an H pulse.

A commercially available 96LO2 type IC can be used for this multivibrator.

This 31250 Hz pulse train is connected to a NOR gate 60 with one input terminal grounded and two inverters 56,
the first counter 38 through a plurality of delay means consisting of 58
It is applied to the A data (preset) input terminal (ADATA) of A.

However, the other data input terminals of counter 38A and the data input terminals of counters 38B and 38C are grounded.

First, second and third counters 38A, 38B and 38C
are simultaneously loaded by a signal applied from the synchronizing means 16 via another input terminal 66.

Therefore, when the button is pressed at the start of fields 1 and 3, the initial value of the counter is "1", that is, 0000 0000 00
It becomes 01.

In addition, in counting, the lower 4 bits correspond to the output of the counter 38A (QAtQB+Qa and QD), the central 4 bits correspond to the output of the counter 38B, and the upper 4 bits correspond to the output of the counter 38C.

Thus, if field 1 or 3, only the QA of counter 38A is set to a "high" level 1 at the beginning of that field.

Since multiplexer 46 is controlled by the lower two bits of the output address signal from counter 38 and PROM 44 is addressed by the next eight bits of the address signal from counter 38, the Qc and QD outputs of counter 38C are not used. Please note.

If it is at the start of field 2 or 4, the initial value of the counter is count "0", i.e. oooo oooo ooo
.

is set to

In this way, when the button is pressed at the beginning of the odd field and the even field, the initial value of the counter 38 is set to count "1" and "0".
'' is set because a pulse with twice the frequency of the H pulse is applied to the A data input terminal of the first counter 38A, and an odd multiple of the period of this pulse is the period of the ■ pulse. .

Thus, after a "1" or rOJ is set at the beginning of each field, the PROM 44 addresses corresponding to each half line are sequentially selected.

A commercially available 828129 type IC is suitable for this FROM.

The parallel output data of PROM 44 is converted into serial data by multiplexer 46, which is a 74S153 type IC.

Since the PROM 44 is a 256 x 4 bit array, the multiplexer 46 sequentially selects each bit of the 4-bit output of the PROM 44 using the lower two bits of the counter, that is, the outputs QA and QB of the counter 38A, and outputs them to the line 68. In the block diagram of FIG. 1, a discriminator 70, a filter 72, and a comparator 74 are used to detect the absence of color signals in a predetermined number or more lines of a television signal.
, counter control logic stage 76, line sequential test stage 7
8, a counter 80, a counter logic stage 84, a flip-flop (FF) 82, and a mode control stage 102 are provided, but since these are not directly related to the present invention, their explanation will be omitted.

In addition, the crystal oscillator 104 is connected to the circuit 3 even if there is no input subcarrier.
Add subcarriers to 0 and 32.

Effects of the Invention As described above, the color television apparatus of the present invention has the ability to adjust the color according to the presence or absence of a color signal in each half line of one field of the television signal, in accordance with the system standard of the television signal. Since the information is stored in the storage means, by reading this storage means in synchronization with the input television signal, the information can be accurately divided into two parts without using the vertical line discrimination signal of the television signal, the white reference, etc. Color information for each line can be obtained.

Further, when the vertical pulse is generated, the address signal for the storage means is set to the first initial value for the odd field,
For even fields, the second initial value is different from the first initial value in the least significant bit, so in order to obtain color information for two fields in consideration of interlaced scanning, the storage means only needs one field. It is only necessary to memorize the color information for minutes.

Therefore, the configuration is simple and inexpensive.

Furthermore, the present invention only changes the storage contents of the storage means,
It is also applicable to various/stem standards other than the SECAM system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example in which the present invention is applied to a SECAM system, FIG. 2 is a waveform diagram showing field blanking of a composite SECAM signal, and FIG. 3 is a block diagram showing a preferred embodiment of the present invention. In the figure, 016 is a synchronizing means, 38 is an address signal generating means, 44 is a storage means, and 51 is a pulse generating means.

Claims (1)

[Claims] 1. A synchronizing means for generating horizontal and vertical pulses in response to a human-powered television signal, a pulse generating means for generating a pulse signal with a repetition frequency twice that of the horizontal pulse from the synchronizing means, and a system standard for the television signal. storage means that stores information regarding the presence or absence of a color signal in each half line of one field of the television signal according to the above, and an address signal of the storage means that counts the pulse signals from the pulse generation means. and address signal generating means for generating the vertical pulse, the address signal generating means sets the address signal to the odd field as a first initial value and sets the address signal to the even field as a first initial value when the synchronizing means generates the vertical pulse. The color television apparatus is characterized in that the information is obtained from the storage means as a second initial value having a least significant bit different from the first initial value.